Variable pitch propeller



' Feb. '12, 1935; V L, F; 0.51m 1,9903

' VARIABLE PITCH rnorsnmm Filed April 12, 1933 4 Shanta-Sheet ll lNVENTOR UZANDRO ERNANDEZ i c TTORNEY Feb. 12, 1935.

L. F. CASTRO VARIABLE PITCH PROPELLER Filed A ril 12, .1935

4 Staph-Shoat 2 INVENTOR ATTORNEY T Feb. 12, 1935. L. F. CASTRO VARIABLE P ITIGH PROPE'LLBR 4 sheets-snub: s

Filed April 12, 1933 w 8 n9 r #2 B. Wm

LIZANDRO FERNANDEZ CAS R0 7 I W E ATTORNEY Fe 12,- 1935. L, F. C ASTRO VARIABLE PITCH PRQPHLLSR 4 Shuis -Sh ut 4 Filed April 12, 1955 INVENTGR Patented Feb. 12, 1935 UNITED STATES PATENT OFFICE 1,990,814 VARIABLE rrron PROPELLER Lizandro Fernandez Castro, San Francisco, Calif. Application April 12, 1933, Serial No. 665,131

for varying the pitch of the propeller while inaction.

Another object is to automatically maintain the selected pitch.

A iurtherobject is to provide responsive means for positively indicating the degree of pitch at which the propeller is actually operating.

Other objects and advantages will appear as the description progresses.

In aircraft practice, controllable pitch propellers have demonstrated greatly increased overall eillciency of propulsion.

There are so many variables in the conditions under which aircraft propellers operate that a propeller with a fixed pitch is at best a compromise between the extremes.

In the take ofi a fine pitch permitting high engine speed is desirable. At cruising speed the pitch of the propeller should be in ratio to the best working engine speed. hides a coarse pitch is desirable. In landinga fine pitch or neutral enables the pilot to keep his motor operating at .acceleratable speed to meet emergencies. A further safety element can be introduced by reversing the propeller with suitable engine speeds to retard the progress of the craft.

It is important also tively that the propeller blades have responded to the variable control as indicated by the responsive index forming part 01! this invention.

In this specification and the accompanying drawings, the invention ierred. form. It is to be understood, however, that it is not iim'ted to this form because it may be embodied in other forms and applications without departmg from the spirit of the invention as defined in the claims following the description.

in the ion: sheets of drawings:

Fig. i is a side elevation diagrammatically illustrating a variable pitch airplane propeller, "remote control and responsive index,

7 constructed and combined in accordance with this invention and applied to-the forward portion of an airplane shown in dotted lines.

Fig. 2 is an enlarged fragmentary detail of the hub-of the propeller partly broken away in vertical section to disclose the inner assembly of the blade control mechanism.

Fig. 3 is a horizontal section of the same taken on the line 131-111, Fig. 2.

Fig. 4 is an enlarged detail in front eleva- In the higher altithat the pilot know posiis disclosed in its pre-' 4- Claim. (Cl. 170-163) tion of the control valve of the remote control mechanism.

Fig. 5 is a vertical section'of the same taken on the line V-V, Fig. 4 Fig. 6 is a rear view Fig. 4. Fig. 7 is a cross section of the valve taken on the line VII-VII, Fig. 5.

. Fig. 8 is a similar view taken on the line VIII- VIII.

' In detail the construction shown in the drawings, referring to Fig. 2, comprises the tapered motor shaft 1 having the key- 2 engaging the to.- pered hub 3. This hub is flanged and bolted at 4 to the tubular housing 5. sion 6 of the hub engages the key and is also flanged and bolted at '1 to the housing 5. The hub is forced onto the shaft and locked by the annular nut 8 threaded onto the end of the shaft.

The housing has the tubular sockets 9-10 to receive the annular antifriction bearings 11-12. The roots 13-14 of the propeller blades, respec-. tively, extend into these sockets and frictionally engage the cones of the opposed bearings 11-12.

The inner ends of these roots have annular grooves therein to receive split collars such as 15 which are flanged to engage the bearings 12 to take the centrifugal pull of the propeller blades.

The external portions of the roots are similarly grooved to receive the threaded split collars 16- l? fixed to the roots by the pins 18 respectively. The running nuts 19-20 bearing on the caps 21- 22 interposed between them and the cones of the bearings 11-11 respectively, provide means for taking up all lost motion in the bearings 11-12 to prevent chattering in the propeller blades when in operation. The adjustment of these nuts is fixed by the lock nuts 19'-20'. Thus mounted in the bearings, the propeller blades are free to rotate on an axis transverse to the axis of the motor shaft 1.

The normal pitch of propellers is determined by the duty to be performed and the angle of the blades fixed accordingly. Since the conditions of night, altitude, take-oi and landing vary, it is desirable to vary this normai angle to meet immediate conditions as previously stated.

Referringto Fig. 3, the transverse pins 23-24 extend, through the roots of the blades respec tively and are fixed therein by the set screws 25, threaded into the roots and forcing the blocks 26 into annular grooves in the pins. The heads 27-28 of these pins protrude to receive the pivots 29-30 to which the links 31-32 are pivoted at one end. Their opposite ends are pivoted at 31- 32' to the plungers 33-34 guided in holes in the hub 3 parallel with the axis of the shaft 1. The ends of these plungers are fixed to the revolvi1 5 hollow thrust collar 35 by the bolts 36-37 of the valve shown in 39, slidable locked by theset screws 36'-37'. These bolts 36-37 screwed into the in the hub 3, see Fig. 2. In operation, the normal thrust ofthe propeller blades urges the control assembly toward positions indicated in dotted lines in Fig. 3 which is the basic pitch. The full lines in Figs. 2-3 indicate the "neutral or zero" pitch. The position indicated in Fig. 1 is full pitch ahead.

lead 48 of the inlet port 41, see Fig. 7.. The sleeve valve 45 is provided with the operatpiston rods respectively, extending through the stufling boxes 63-64. These cylinders are cross-connected by the tube 65 between stumng boxes tube 66 with the outlet port 42 valve. l

The piston rods 61-62 are respectively pivoted ends of which are pivoted at 69-70 to the motor block.

These levers are connected by the links 71-72, pivoted thereto at 73-74 respectively, and ad- Justably connected to the t plate 39 see site direction.

The handle control .40 and the valve assembly the propeller toward slots in the ends 01 the levers 67-68 the other 106, straddles ate the power units 59-60-to manually adjust collar 86 to permit it to oscillate freely when theresponder valve is turned. he arm 90 has a bifurcated head clamped upon T the end of lected by the handle 49.

The clamp 93 is contracted about the end of the valve body 40 to hold the adjustable bracket 94 in the split end of which the tube 95 is clamped, see Fig. 6. This tube extends forward and is anchored at 96 to the motor block in proximity to the lever 67.

peller assembly.

Any change in the pitch of the propeller blades is communicated through the movement of this wire and is indicated ously. with the movement of the yalve 45.

The handle 49 has the index pointers 100-101 registering with the graduated scale 92. The rear ot'the quadrant 51 is provided with holes 102 is guided in the recess 106 in the handle. The springs 107-107, expanding between the heads or the detents 103-104, respectively, and the the block 105, and has the inon the scale 92 synchronclined ends 110 engaging in front 01' the lugs 111.

The stem 112 is fixed in the yoke and operated by the button 50 against the expansion 01' the lows:

In Fig. 4, with the handle index 100 on the zero by the handle 49.

- point control mechanism is locked The propeller is set at its norsuitable for higher altitudes point A, the entire by impounded oil. may coarsest pitch or cruising.

If it is desired to decrease the releases the latch button 50 and pushes the handle 49 forward, see Fig. '7. The forward movement of the handle rotates the control valve 45 which brings its port 46 into registry with the passage port 81 in the responder valve 80. The oil pressure then flows through the ports 41, 4'1. 81, 46, 44 and 42, through the tubes 66 and 65 into the power units 59-60. The pistons in these units operate the interposed lever assembly to'retract the collar 35 and decrease the pitch of the propeller blades in unison. The handle 49 is then locked at the selected degree of pitch desired as indicated by the index 100 on-the graduated scale 92, for instance "7" of decreased pitch.

When the propeller has responded to the charge" of oil selected-by e handle 49, the wire 9''! backs up through the tube 95 and actuates the "responder mechanism which rotates the plug valve 80 and moves the index 91 to 'l" on the scale 92. vThe forward rotation of this valve 80'cuts off the passage port 81 at 46 and impounds the oil in the system forward of the control valve, which locks the propeller pitch at I.

Should there be any oil leakage between the control valve and the power units 59-60, the index 91 would move backward toward the zero B which would restore the registry of the ports 46-81-44 and replace the lost oil which would also automatically restore the propeller pitch to 7.

It the handle index 100 is moved forward to on the scale 92, the propeller pitch will be flattened out to neutral. This condition is advantageous while the motor is warming up and in landing" since a good working motor speed can be maintained without any propeller thrust.

when the index 100 is at 15 or neutral", the index 91 or the responder is also at 15. To increase the pitch from neutral" to a coarser pitch, the handle 49 is moved rearward registering pointer 101 on graduation 92 on quadrant 51.

This rotates the control valve 45 and brings its discharge ports 83-84 into registry with the passage 82 and the discharge port 43.

The propeller in assuming its coarser pitch, due to its normal urge in that direction because 0!. impinging against the air, causes the forward movement of the collar 35. This moves the pls tons in the power units to discharge the impound ed oil through 83-82 and the'retum outlet 43 back into the oil circulating system through the tube 55. This reverse movement-of the pistonsthe wire 9'? which causes a is communicated to rotation oi the responder valve 80 synchronously with the rotation of the control valve 45. when the responder valve 80 has overtaken the control valve, it has moved the passage port 82 out of registry with the port 83 which arrests the further movement of the escaping oil and holds the propeller pitch at any degree selected when the pitch has attained its maximum with the collar 35 abutting the end of the hub 3, the responder index 91 registers zero B on the scale 92 and index 100 on zero A. This puts the passage ports 82 and 81 in the positions shown in Figs. 7-8 with both pitch, the pilot sure means including inlet and outletports 1 41-42-43 closed, with the propeller working full thrust ahead.

In maintaining a handle 49 is moved until either 0! the indices 100 or 191 registers the desired degree depending upon whether the pitch change is from coarse to neutral or vice versa. When the index 91 responds to the same degree, the handle can be movedto zero A which looks the propeller against further pitch changes in either direction, except that leakage will be automatically restored as previously described.

In taking off or in climbing-where the increased power incidental to high motor speed is desirable, the propeller pitch can be decreased to the capacity of the motor to maintain its maximum power. The advantages of variable pitch propellers is now well established and their general adoption is dependent upon reliable and positive control such as provided in the present invention.

Having thus described the invention, what I claim and desire to secure by Letters Patent is; e

1. A variable pitch propeller including a fluid pitch of said propeller; a manual control valve assembly in said pressure means including having cut-ofl' ports therein; and a responder valve having ports cooperative with said cut-oil ports, and actuated by variations in the pitch of said propeller in synchronism with said control valve independent or said manual control.

2. In a variable pitch propeller including a fluid pressure means adapted to vary the pitch of said propeller; a manual control assembly in said presa control valvehaving cutoft-ports therein; a graduated scale on said assembly; a responder valve having ports cooperative with said cut-off ports and actuated by variations in the pitch of said propeller in synchronism with said control valve independently of said manual control; indexes or. said control valve and responder valve respectively and registering on said scale.

3. In a variable pitch propeller including a fluid pressure actuating unit adapted to vary the pitch of said propeller; a fluid pressure pump; a control valve block having inlet, outlet and return ports; conduits extending between said pump and said inlet and return ports respectively, and between said outlet port and said unit; a control valve having cut-oi! ports coacting with said inlet, outlet and return ports; a responder valve actuated by variation in the pitch of said propeller independent of said control valve, movable within said control valve and adapted to move in synchronism with the movement or said control valve.

4. In a variable pitch propeller including a fluid pressure actuating unit adapted to vary the pitch of said propeller; a fluid pressure pump; a control valve block having inlet, outlet and return ports; conduits extending between said pump and said inlet and return ports respectively, and between said outlet port and said unit; a control valve having cut-oi! ports coasting with said inlet. outlet and turn ports; a responder valve actuated by variation in the pitch of said propel ler by means independent or said control valve and movable within said control valve and adaptin synchronism with the movement of said control valve; and indexeson said control valve and responder valve respectively.

LIZANDRO FERNANDEZ CASTRQ' selected pitch angle, the 

